Before, the Church has no concrete doctrines yet. There are lot of teachings which is not aligned what the Bible says. Some group leaders has more authoritative than the Bible that is why their member will obey them even if they know that it is not the Bible says and of course, they do not have choice but to obey their leaders. This is sad for the Church that there are practices like this before and I can see it until now in some denominations.
This time, God used some people to correct those teachings and mold our doctrines that will align what the Bible says. They are people who are brave to face the death because in their time, the leader of the Roman Catholic Church has the power to execute them and excommunicate them from the Church. Yes, some of them died, some are excommunicated. They are not afraid because they know that they are in the truth. One man that I was impressed most is Martin Luther. God has opened his mind and he realized that an indulgence is wrong. He fought for it and it drove him to write 95 theses and it really help the people to opened their minds also about it and it success. I was amazed in his braveness to face the Pope and many leaders who has authority over him and ask him to recant from what he wrote in his theses and he did not and instead he stands in his faith that God will protect him in times of troubles.